Method of Working Gemstones

ABSTRACT

The invention provides a method of gemstones working enabling rapid gemstone working member exchange and gemstone processing sequence continuation without the need to level the gemstone or the working member. The invention also provides a rotatable support having an axis of rotation and a registering feature. The registering feature precisely positions and aligns an interchangeable abrading article so that its working surface rotates in a predetermined plane, which has fixed position relative to the gemstone.

FIELD OF THE INVENTION

The present invention relates to the field of gemstone working and inparticular, to a method of gemstone working enabling rapid gemstoneworking member exchange and gemstone processing sequence continuationwithout the need to level the gemstone or the working member.

BACKGROUND OF THE INVENTION

Grinding and polishing are the most common gemstone working (shaping)operations. Gemstones can be polished or worked in different ways. Mostcommonly, gemstones are polished or worked mechanically on a fastrotating metal working member or scaife. A scaife is a heavy, cast iron,horizontally spinning wheel with a working surface impregnated with oiland diamond powder.

To obtain the maximum gem brilliance, the facets must be the right size,have correct angles to each other, and their surfaces must be finelypolished with irregularities not larger than a few nanometers. Forgemstone working purposes, the gemstone is mounted on a dop held by atang and it is leveled with respect to the working member. The gemstoneleveling procedure provides for the correct angles and right size of thefacets. The term gemstone includes diamonds, other precious andsemi-precious stones.

European Patent No. 0 299 692 B1 to Blondeel teaches that for gemstonepolishing, the scaife axial (vertical run out) position stability isimportant. Diamonds are especially sensitive to vertical run out. If theaxial run out of the diamond impregnated surface of the scaife exceeds±0.005 mm the polished gemstone (especially if it is a diamond) may befractured. Blondeel uses magnetic levitation and certain predefinedrotational frequencies to stabilize the scaife.

As the number of diamonds polished on the same scaife increases, thediamond impregnated surface of the scaife wears out. Sometimes groovesare formed in it and the scaife has to be renewed. For the purpose ofrenewal, the scaife is removed from the polishing machine and deliveredfor so called maintenance. The diamond impregnated surface is removedand a new surface, that possesses the same flatness as the originalscaife working surface, is formed. Following formation of a new surface,the scaife has to be balanced. Handling of the scaife, which weighs15-18 kilograms, is not an easy procedure.

Not every renewed scaife is suitable for polishing diamonds. In manycases grooves are formed on the diamond impregnated surface of thescaife. When such a scaife is sent for maintenance, the grooves are notcompletely removed. This practice is adopted because users do not wantto waste the unused diamond impregnated part, which would be lost if thegrooves were removed completely. Instead, the surface of the scaife ispolished. This makes the surface smooth but does not remove some of thedeeper grooves. If the remaining deeper grooves cause differences in theflatness of the renewed diamond impregnated surface exceeding ±0.005 mm,the polishing process may result in chipped culets and imperfect facets.

When a renewed or another scaife having the same or different, diamondpowder grade required by the process sequence, is mounted in a diamondworking machine the diamond impregnated surface is at a different heightplane that the original height plane. This dictates a need for levelingof the gemstone to be polished. Without a proper leveling procedure, thepolishing facet angle will be changed and the total internal reflectionconditions will not exist. The brilliance of the polished gemstone willbe adversely affected. The leveling operation takes time and reduces themachine throughput.

U.S. Pat. No. 5,503,592 to Neumann attempts to solve the problem ofusing working members having different diamond powder grades. Neumanndiscloses a gemstone working apparatus which includes a rotatable base,two gemstone working members including a first gemstone working memberwhich defines a first gemstone working surface adapted for removablemounting on the base; and a second gemstone working member which definesa second gemstone working surface, of a different grain size than thatof the first gemstone working surface. The second member is adapted forremovable mounting on the base concentrically with the first gemstoneworking member and has height adjustment means that brings the secondworking surface into planar alignment (leveling) with the first workingsurface. The surface of the second member wears quicker than the surfaceof the first member. The second surface can however, be replaced.According to the invention this allows performing a sequence of gemstoneworking operations including second surface replacement in the course ofpolishing. The replacement however, requires realignment of the surfacereplaced, which is performed by adjusting the height of the surface ofthe second working member. Replacement of the first member is performedin a conventional way.

The surface height adjustment of the second member must be performedwith micron accuracy; otherwise, the working of a diamond would beimpossible. Such realignment is difficult or nearly impossible toperform since both sides of the second member are diamond impregnatedand do not provide the desired planar contact between the engagingsurfaces. The gap between the first and second surface is always presentmaking this method not practical for working of diamonds and certainother fragile gemstones.

The background art does not teach or suggest a method of working agemstone and exchanging the working member that does not requireleveling of the gemstone or the working surface of the new workingmember. The diamond working industry would benefit if such a methodwould exist. The diamond industry would further benefit if hardwareenabling a method of exchanging the working member that does not requireleveling of the gemstone or the working surface would exist.

SUMMARY OF THE INVENTION

The present invention provides a method of working a gemstone on agemstone working member exchange or replacement that does not requireany maintenance and leveling procedures.

It is therefore an object of the present invention to provide a methodof gemstone, and particularly diamond, working that enables gemstoneworking member exchange and gemstone processing sequence continuationwithout the need for leveling the gemstone or the working member.

An additional object of the present invention is to provide a workingmember exchange or replacement where leveling of the gemstone beingworked or of the working member in the course of a gemstone processingsequence is not required.

It is a further object of the present invention to provide a gemstoneworking method that could be implemented on existing gemstone workingmachines.

An additional object of the present invention is to provide a gemstoneworking apparatus facilitating utilization of the gemstone workingmethod.

According to the teaching of the present invention, the method ofworking a gemstone includes providing a rotatable support having an axisof rotation and a registering feature. The registering feature isoperable to determine a registering plane perpendicular to the axis ofrotation. The method further includes providing a fixture configurationoperable to hold the gemstone at an adjustable level relative to theregistering plane, and placing the gemstone to be held in the fixtureconfiguration. The method also includes providing a plurality ofinterchangeable abrading articles, each of which has a working surfaceand each of which is operable to couple to the rotatable support.

According to a further teaching of the present invention, the methodincludes coupling a first abrading article of the plurality ofinterchangeable abrading articles to the rotatable support. The couplingis followed by leveling of the fixture configuration prior to using thefirst abrading article, setting the adjustable level to a working level,and working the gemstone on the working surface of the first abradingarticle.

In agreement with the teaching of the present invention, the methodfurther includes; replacing the first abrading article by a secondabrading article of the plurality of interchangeable abrading articles;coupling the second abrading article to the rotatable support andworking the gemstone on the working surface of the second abradingarticle while maintaining the adjustable level at the working level,without repeating the leveling prior to using the second abradingarticle.

As used herein, the term “rotatable support” may be understood as asupport having an axis of rotation and a “registering feature”. The term“registering feature” denotes a feature of the rotatable support, whichprecisely positions and aligns the abrading article so that its workingsurface rotates in a predetermined plane, which has a fixed positionrelative to the gemstone. The predetermined plane may be a “registeringplane” perpendicular to the axis of rotation of the rotatable support.

In agreement with the teaching of the present invention, the registeringfeature is not associated with any specific hardware. The registeringfeature may be a combination of flat and cylindrical surfaces, a singlesurface such as a convex, concave or conical surface and any otherarrangement that ensures precise position and alignment of the abradingarticle so that its working surface rotates in a predetermined plane.

According to the teaching of the present invention, the working surfaceof the abrading article is coated with abrasive material. The abrasivematerial is diamond powder. The diamond powder may be of a single gradeor sections of the abrading article may be coated by different grades ofdiamond powder. Optionally, the working surface of each of the pluralityof abrading articles may be coated by diamond powder of differentgrades, as may be required by a particular gemstone working sequence.

In agreement with the method of the present invention, the distance fromthe working surface to the registering plane is substantially identicalfor each of the plurality of interchangeable abrading articles whencoupled to the rotatable support. According to one exemplary embodiment,the rotatable support consists of a single material. According toanother embodiment, the rotatable support may consist of more than onematerial.

According to the method of the present invention, the interchangeableabrading article is operable to couple to the rotatable support via theregistering feature.

In agreement with the method of the present invention, the working isselected from the group consisting of polishing and grinding.

The present invention provides for using the method of working agemstone in existing conventional gemstone working machines. It alsoenables and promotes construction of gemstone working apparatusescharacterized in that they are specially adapted for use of the method.

When the working surface of the interchangeable abrading article wearsout or becomes unusable, the abrading article is simply replaced byanother abrading article. Use of an interchangeable abrading articleeliminates the need for working member maintenance.

Replacement of the abrading article does not change the distance fromthe working surface to the registering plane and does not cause the needto level the gemstone being worked or the abrading article. Thisshortens the time required for working a gemstone and reduces thegemstone working cost.

The rotatable support may be built in such a way that it installs on theexisting gemstone working machine in a way similar to a conventionalscaife. This enables application of the method of working a gemstone toexisting gemstone working equipment while preserving the earlier madeinvestments and further reducing the gemstone working costs.

The cost of the interchangeable abrading article is low when compared toconventional scaife renewal cost, allowing its disposal upon use. Thissimplifies material handling and further reduces gemstone working costs.

BRIEF DESCRIPTION OF DRAWINGS

The foregoing and other objects, features and advantages of theinvention will be apparent from the more detailed description of theexemplary embodiments of the invention, as illustrated in theaccompanying drawings in which like reference numbers refer to the sameparts throughout the different figures. The drawings are not necessarilyto scale. Emphasis is placed upon illustrating the principles of theinvention.

FIGS. 1A, 1B and 1C illustrate some elements of prior art gemstoneworking method;

FIGS. 2A-2D are schematic illustrations of exemplary embodiments of thehardware enabling the method of working a gemstone of the presentinvention;

FIG. 3 is a schematic illustration of an abrading article coupled withthe rotatable support which is a part of the present invention, and

FIG. 4 is a schematic illustration of the method of working a gemstoneof the present invention.

DETAILED DESCRIPTION OF THE INVENTION

By way of general introduction, before addressing the drawings indetail, it should be appreciated that certain exemplary and non-limitingimplementations of the present invention provide a method of working agemstone. The invention also provides the hardware enabling the methodof working a gemstone of the present invention.

Reference is now made to FIG. 1, which illustrates some of the elementsof a prior art method of working a gemstone. FIG. 1A shows a spindletype working member or scaife 100, commercially available from NOVEXGmbH., Nuremberg, 90473 Germany and other sources. Flat scaife 112, asshown in FIG. 1C, also exists. Working member 100 is a heavy, cast iron,horizontally spinning metal wheel having a rotational axis or shaft 102;a section 104 of rotational axis 102 is adapted to engage a gemstoneworking machine with a source of rotational movement. Working member 100further has a large and relatively thick disk-like section 108 theworking surface 110 of which is impregnated with diamond powder.

Fixture configuration 116 involves one or more devices for holdinggemstone 120 at a particular angle and height relative to workingsurface 110. Configuration 116 may include a dop 122 and a tang 124.Fixture configuration 116 may be a hand-held block that travels back andforce in the direction indicated by arrow 130 on horizontal surface 128.Alternatively, configuration 116 may be an automatic block that movesgemstone 120 back and force on surface 128.

As the number of gemstones polished on the same working member (scaife)increases, the diamond impregnated surface 110 of the working memberwears out or becomes unusable. In order to renew working surface 110,working member 100 is removed from the gemstone working machine anddelivered for maintenance where diamond impregnated surface 110 isremoved and a new surface 110 is formed (FIG. 1B) that possesses thesame properties and flatness as the original working member surface 110.Because of the maintenance process, some of the thickness of cylindricalsection 108 of working member 100 is removed and working surface 110′operates in a different plane from the one in which working surface 110operated. Gemstone 120 meets working surface 110′ at a different angleand height that do not correspond to the required facet angle. Thisdictates the need for releveling of the gemstone to be worked.

A similar need for leveling the gemstone exists when another scaiferequired by the gemstone working sequence having the same or different,diamond powder grade, is mounted in a diamond working machine.

The present invention provides a method of working a gemstone andparticularly diamonds, enabling gemstone working member exchange andgemstone process sequence continuation without the need to level thegemstone or the working member. The term “working” in the context of thepresent invention includes polishing and grinding of gemstones and otherprecious and semi-precious stones.

According to the teaching of the present invention, the method ofworking a gemstone includes providing (Block 220, FIG. 4) a rotatablesupport 140 (FIG. 2A) having a support section 138, axis of rotation 142and a registering feature. The term “registering feature” denotes afeature of the rotatable support, which precisely positions and alignsabrading article 160 so that its working surface 162 rotates in apredetermined plane, which has a fixed position relative to thegemstone. The predetermined plane may be a “registering plane” and theregistering feature is operable to determine a registering plane 148perpendicular to the axis of rotation of rotatable support.

The registering feature is not associated with any specific hardware. Inone exemplary embodiment shown in FIG. 2A, a combination of flat surface146 of rotatable support 140 and a cylindrical section 144 with axis ofrotation 142 provide the function of the registering feature. In anotherexemplary embodiment (FIG. 2B) a combination of flat surface 152 ofrotatable support 150 and cylindrical section 154 of protrusion 156 ofsupport 150 provides the function of the registering feature. FIG. 2Cshows a rotatable support 170 having a convex (concave) surface 172 andFIG. 2D shows a section of axis of rotation or shaft 182 having conicalsurface 184. Conical surface 184 may also have a key or a number ofgrooves engaging complementary sections of abrading article 180.Surfaces 172 and 184 may provide the function of the registeringfeature.

The method further includes providing a fixture configuration 116 (Block220) operable to hold gemstone 120 at an adjustable level relative tothe registering plane 148, and placing gemstone 120 into fixtureconfiguration 116. The method also includes providing a plurality ofinterchangeable abrading articles 160. Each of abrading articles 160 hasworking surface 162 and each abrading article 160 is operable to couplewith rotatable support 140. Working surface 162 of abrading article 160is coated with abrasive material. The preferred abrasive material isdiamond powder. Any method of coating by diamond powder such asimpregnation, electroplating or use of adhesive materials is suitablefor coating of surface 162. Further to this, working surface 162 maycontain sections having different grades of diamond powder for makingall gemstone working sequences on the same working surface. The workingsurface of each of the plurality of abrading articles may be coated bydiamond powder of different grades, as may be required by a particulargemstone working sequence.

Generally, an abrading article may have different forms, although thesimplest form of abrading article 160 is a disk-like article. Surface162 is a flat surface having a high degree of flatness. Flatness ofsurface 162 is especially important if the abrading article rests onflat surface 146 of rotatable support 140. Typically, abrading article160 would have a thickness of 1 mm to 6 mm. Rotatable support 140provides the necessary stiffness keeping working surface 162 flat whenworking a gemstone. Abrading article 180 (FIG. 2D) has no support andshould be thick enough not to wobble under the pressure of the workedgemstone.

According to a further teaching of the present invention, the methodincludes coupling (Block 222, FIG. 4) a first abrading article 160 ofthe plurality of interchangeable abrading articles to rotatable support140 and retaining it on rotatable support 140. Different retainingmechanisms may be operable to retain the abrading article on therotatable support. FIG. 2A shows an exemplary embodiment where permanentmagnet inserts 200 distributed across rotatable support 140 retainabrading article 160, which, in this case, should be made of aferromagnetic material. Electro-magnetic inserts may replace permanentmagnet inserts 200. Alternatively, nut 158 a in FIG. 2B engages thread158 b to retain abrading article 160. FIG. 2D is an illustration of asimilar retaining mechanism where nut 186 a engages thread 186 b toretain abrading article 180. In yet another embodiment illustrated inFIG. 2C, vacuum provided by vacuum pump 178 through rotary joint 176retains abrading article 172 on rotatable support 170.

FIG. 3 is a schematic illustration of abrading article 160 coupled withrotatable support 190. Vacuum provided by vacuum pump 178 through rotaryjoint 176 retains abrading article 160 on rotatable support 190.

(Block 224, FIG. 4) To set the adjustable level to a working level afterthe coupling operation and prior to using first abrading article 160,fixture configuration 116 is leveled. After this, working (Block 226,FIG. 4) of gemstone 120 on working surface 162 of first abrading article160 may begin.

Generally, one abrading article 160 may be sufficient for working anumber of gemstones. There may be cases where only one or more facets ofa gemstone were worked on a particular abrading article and the articlewears out becoming unusable or the gemstone working sequence requires anabrading article coated by different grades of diamond powder. (Block228, FIG. 4). In agreement with the teaching of the present invention,the method further includes (Block 232, FIG. 4) replacing first abradingarticle 160 by a second abrading article of the plurality ofinterchangeable abrading articles 160; Coupling the second abradingarticle 160 to rotatable support 140 and working gemstone 120 on theworking surface of second abrading article 160 while maintaining theadjustable level at the working level. The leveling process is notrepeated prior to using the second abrading article.

In agreement with the method of the present invention, the distance fromworking surface 162 to registering plane 148 is substantially identicalfor each of the plurality of interchangeable abrading articles whencoupled to rotatable support 140 and working surface 162 that maycoincide with registering plane 148. In any case, the vertical run-outof the registering plane may not exceed ±0.005 mm. In order to achievethis run-out, both the abrading article and the rotatable supportmanufacturing should be subject to tight process control. Manufacture ofthe abrading article may involve repetitive grinding and thermalprocessing steps that provide the desired flatness, accurate dimensionsand prevent any stress accumulation that may cause abrading article 160to warp and lose flatness.

Flat surfaces 146, 152 and 192 (FIG. 3) of rotatable supports 140, 150and 190 may consist of a homogeneous single material. This simplifiessurface processing. In prior art solutions, such as U.S. Pat. No.5,503,592 to Neumann, the magnetic ring and steel support on which thering rests are both in direct contact with the second member surface.Since the magnetic ring and its steel support are made of two differentmaterials, they cannot be ground to the same surface quality and levelof flatness.

FIG. 2A illustrates an exemplary rotatable support 140 of the presentinvention having magnetic or electromagnetic inserts 200. There is nodirect contact however, between permanent magnet inserts 200 and any ofthe surfaces of abrading article 160. Magnetic inserts 200 are insertedin troughs made in body 150 of rotatable support 140. A material layerexists between magnetic inserts 200 and the lower surface of abradingarticle 160. This method of insertion of permanent magnets provides ahomogeneous single material structure to surface 146, which may be thusmanufactured with greater accuracy and at a lower expense. Use ofpermanent magnets or electromagnets necessitates use of ferromagneticmaterial for the abrading article. For other types of retentionmechanisms, the abrading article may be made of a non-magnetic materialor composite material meeting the above-described manufacturingrequirements.

As previously indicated, a single material structure simplifiesrotatable support manufacturing and enables manufacturing rotatablesupports with greater accuracy meeting the method requirements.Generally, the rotatable support may consist of more than one material.For example, vacuum orifices may be inserts and surfaces 172 (FIG. 2C)and 184 (FIG. 2D) that may have keys or inserts (not shown) made ofdifferent materials.

The present invention provides for using the method of working agemstone in existing conventional gemstone working machines. FIG. 2Aillustrates an exemplary form of rotatable support 140 having a formsimilar to prior art working member 100 (FIG. 1A) that includes asection 104 adapted to engage a source of rotational movement of aconventional gemstone working machine. Such form of rotatable support140 allows for using an abrading article of the present invention withexisting gemstone working machines. The exemplary form of rotatablesupport 140, similar to the conventional working member, was selectedfor demonstration purposes only. As demonstrated, other forms and shapesof the rotatable support are possible.

The present invention enables and promotes construction of gemstoneworking apparatuses characterized in that they are specially adapted forusing the method of working gemstones of the present invention. In suchan apparatus, the rotatable support is in permanently engaged with asource of rotational movement of the gemstone working apparatus andgenerally is not replaced or removed from the apparatus. In addition,the apparatus includes a source of rotational movement, gemstoneholding, and leveling means.

The disclosed method of working a gemstone and particularly diamondsenables gemstone working member exchange and gemstone processingsequence continuation without the need to level the gemstone or theworking member.

Replacement of the abrading article does not change the distance fromthe working surface to the registering plane, which is substantiallyidentical for each of the plurality of interchangeable abrading articleswhen coupled to the rotatable support and does not cause the need tolevel the gemstone being worked or the working surface of the abradingarticle. This reduces the time required for working a gemstone andfurther reduces the gemstone working cost.

The abrading article, which is part of the present invention does notrequire maintenance. When the working surface of the abrading articlewears out it is simply replaced. This eliminates the need to handle aheavy working member, its balancing and transportation and reducesgemstone-working costs.

The cost of manufacturing the interchangeable gemstone abrading articleis lower than the cost of conventional working member (scaife)maintenance. Accordingly, the abrading article may be disposed uponcompletion of its use.

The rotatable support may be built in such a way that it installs onexisting gemstone working machines in a way similar to a conventionalscaife. This enables application of the method of working a gemstone toexisting gemstone working equipment while preserving the earlier madeinvestments and further reducing the gemstone working costs.

While the present invention has been described in detail, it should beunderstood that various changes, substitutions and alterations could bemade hereto without departing from the spirit and scope of the inventionas defined by the appended claims.

1.-21. (canceled)
 22. A replacement scaife for use in gemstone workingoperations, said scaife comprising: a rotatable support comprising aregistering feature operable to determine a registering plane; and adisposable and replaceable abrading article coupling on one side withsaid support and comprising on a second side an abrading workingsurface, and; wherein the abrading article is coupled with the supportsuch that it forms a scaife and the working surface rotates in apredetermined registering plane; and where replacement of the abradingplane by another abrading plane maintains the position of said workingsurface with respect to said registering plane.
 23. The replacementaccording to claim 22, wherein said coupling of said support with saidabrading article is performed via the registering feature.
 24. Thereplacement according to claim 22, wherein said registering plane has afixed position relative to a gemstone.
 25. The replacement according toclaim 22, wherein said working surface of said abrading article iscoated with diamond powder of at least one grade.
 26. A method ofgemstone working said method comprising: a) providing a gemstone workingmachine and replacing a conventional scaife by the replacement scaife ofclaim 22; b) coupling at least one disposable interchangeable abradingarticle to said rotatable support such that said article working surfacerotates in a predetermined registering plane, said plane has a fixedposition relative to gemstone; c) working at least one facet andadjusting said fixture with gemstone with respect to said registeringplane to set a gemstone working level and working the gemstone; d)replacing said abrading article, and wherein replacement of one abradingarticle of a plurality of disposable abrading articles by another doesnot require leveling of said gemstone or said abrading article.
 27. Themethod according to claim 26, wherein the position of said workingsurface with respect to said registering plane when coupled to saidrotatable support is identical for each of said plurality of abradingarticles.
 28. The method according to claim 26, wherein said workingsurface of each of said plurality of abrading articles is coated withdiamond powder of at least one grade.
 29. The method according to claim26, wherein coupling of said abrading article to said rotatable supportforms a device similar to the conventional scaife.
 30. The methodaccording to claim 26, wherein each of said interchangeable abradingarticles is operable to couple to said rotatable support via saidregistering feature.
 31. A method of coupling a gemstone abradingarticle to a rotatable support said method comprising: a) providing aplurality of interchangeable abrading articles, each of which comprisesa working surface and each of which is operable to couple to a rotatablesupport; b) providing a rotatable support comprising a registeringfeature operable to determine registering plane; c) coupling at leastone disposable interchangeable abrading article to said rotatablesupport such that said article working surface rotates in apredetermined plane being in fixed relation with said registering planegenerated by said registering feature.
 32. The method according to claim31, wherein the coupling of the abrading article to the rotatablesupport forms a device similar to a conventional scaife.
 33. The methodaccording to claim 31, wherein the position of said working surface withrespect to said registering plane when coupled to said rotatable supportis identical for each of said plurality of interchangeable abradingarticles.
 34. The method according to claim 31, wherein said abradingarticles are disposable articles.
 35. The method according to claim 31wherein said working surface of each of said plurality of abradingarticles is coated with diamond powder of at least one grade.
 36. Themethod according to claim 31, wherein each of said interchangeableabrading articles is operable to couple to said rotatable support viasaid registering feature.
 37. The method according to claim 31, whereinsaid abrading article rests on flat, homogeneous single materialsurfaces of said rotatable support.
 38. A gemstone working machine, saidmachine comprising: a source of rotational movement; a rotatable supportfor holding and rotating abrading articles and comprising a registeringfeature for coupling with a plurality of abrading articles, each ofwhich comprises a working surface, such that said working surfacerotates in a predetermined plane generated by said registering feature;and wherein said rotatable support is in permanent engagement with thesource of rotational movement.
 39. The machine according to claim 38,wherein replacement of one abrading article of said plurality ofabrading articles by another maintains said working surface in saidpredetermined plane said plane being identical for each of saidplurality of interchangeable abrading articles.
 40. The machineaccording to claim 38, wherein said working surface of each of saidplurality of abrading articles is coated with diamond powder of at leastone grade.
 41. The machine according to claim 38, wherein said articleis a disposable article.
 42. A method of gemstone working said methodcomprising: a) providing a conventional gemstone working machine, saidmachine including: i. a fixture for holding gemstone with a gemstone,and ii. a conventional scaife; b) providing a plurality of disposableinterchangeable abrading articles, each of which comprises a workingsurface and each of which is operable to couple to a rotatable support;c) replacing said conventional scaife by a rotatable support comprisinga registering feature operable to determine registering plane such thatsaid working surface rotates in a said plane; d) coupling at least onedisposable interchangeable abrading article to said rotatable supportsuch that said article working surface rotates in a predetermined planegenerated by said registering feature, said plane has a fixed positionrelative to gemstone; e) working at least one facet and adjusting saidfixture with gemstone with respect to said registering plane to set aworking level and replacing said abrading article, and whereinreplacement of one abrading article of said plurality of abradingarticles by another does not require leveling of said gemstone or saidabrading article.